Geology

Diamond is a polymorph form of carbon. The other form is graphite. For carbon to turn into diamond, 3 factors are needed: time, very high temperature
(around 1,000.00 degrees) and very high pressure above 30 kilobars (kb). The Pressure and Temperature conditions within the earth, are known as
geotherms. Any changes of « P » (Pressure) and « T » (Temperature) within the environment where diamonds are formed, may reverse the cycle back to graphite or gas. The main bearing diamond
rocks are kimberlite (the name proposed by Lewis in 1888 is for the Kimberley district in South Africa), eclogite, lamproite. Diamonds can be formed going down towards the mantle of the earth
(subduction), going up towards the surface of the earth (obduction) and also on impact (meteorites).

The most common shape of kimberlite pipe is « the carrot shape » it also occur as dykes and rarely as sills. Within the kimberlite pipe 3 zones are recognized, the
crater, diatreme and the root zones. The pipes do vary in size, up to 200 hectares. In contrast to kimberlites, which may show some vertical flaring over 1 to 2 kms, Lamproite
bodies are shallower, around 0.50 kms in depth. Many lamproites have a champagne glass shape craters. The difference between kimberlites and lamproites pipe
shapes has important implications for exploration (ore volume calculations).

Click here to see a multimedia presentation of are diamonds transported to the Earth's surface. You will need
to have the Real Player installed to view this movie. If you do not have it, you can download a free version of the Real Player.

Diamonds in meteorites were discovered in Arizona or South Pole and they contained minuscule crystals of diamonds. In 2004, The Harvard-Smithsonian Center for Astrophysics has announced
the discovery of a mass of crystallized carbon formerly known as star BPM 37093, now known as the biggest diamond in the galaxy, fifty light years away from Earth in the constellation Centaurus.

The diamond is estimated to be 2,500 miles across and weighs approximately 10 billion-trillion-trillion carats – a one, followed by 34 zeros =
10,000,000,000,000,000,000,000,000,000,000,000 carats.

The secondary deposits are formed by the weathering of the kimberlite and the lamproite. The diamonds are released from the rock and then, they are transported hundreds of kilometres away to be
found in river beds, beach sands, old river beds (sometime found on top of hills deep jungle forest, deserts, etc...

Diamonds may also have been transported by glaciers and if the journey has been hard, rough and long, they are not to be found as they have been broken and grinded into near dust.